This blog discusses current weather, weather prediction, climate issues, and other topics

Saturday, March 13, 2010

I want a home weather station? What should I buy?

One of the most frequent questions I get is from people wanting to set up a weather station in their home. What should they buy? Where should they install it?

Lets try to tackle these important questions.

Having your own weather observations is really marvelous. There are very large variations in weather locally and you CAN'T assume that your home or apartment has the same conditions as Sea-Tac airport or one of the limited collection of stations presented on TV or in the paper. A few years ago I ran around the city with a bunch of 101 students in specially instrumented cars--temperatures varied by 15-20F on a cold winter night! (the graphic is in my book if you are interested). Having your own observations can help calibrate your gardening...when to put in or protect that delicate plant. Taking weather observations really brings you closer to nature, makes you more sensitive to natural rhythms and variations, makes you a better observer, and has a calming, salubrious effect on your disposition. Yes, weather observers are a happier lot.

One of the great revolutions of the last decade has been the availability of a wide range of weather instrumentation at a reasonable cost, some with near-professional calibration. And the second revolution has been the distribution of many of these observations over the internet. Tens of thousands of individuals around the U.S. put their observations online in real-time, and these are viewable on sites such as weatherunderground.com.

So what should you buy? Well, if you want to invest in very good equipment, we have found that the Davis Vantage Pro hardware is really excellent (see image above). This system can cost you $ 500, but you can often do better with a little internet shopping. If you have extra cash I was get the aspirated thermometer (solar powered fan for the enclosure). You can also get software for connecting the unit to your computer.

Now what if you don't have so much $? No problem. You can buy inexpensive gear with less accuracy that still can tell you a great deal. For example, COSTCO sells Oregon Scientific and LaCrosse weather stations for $ 100-200, with similar prices from others over the web. But you get what you pay for. And many of them have unshielded thermometers, so BE SURE to put then in a shady location on the north side of your residence, out of the rain.

Out of work or just on an allowance? No problem again. You can buy a digital thermometer or an alcohol one for $10, a rain gauge for $5-10, a cloud chart for $5, and a barometer for $25.00. And a pad to record your observations. That is how I started. As did Thomas Jefferson.

For the computer oriented, getting your weather station interfaced with a computer is great fun, and the interfacing software often comes with neat archival and plotting software. But the fun doesn't stop there. You can automatically send your data to groups such as weatherunderground.com so you and others can view it online. In fact, even if you don't have a weather station, you can often get a close-in weather view for your location by going to that site. The map below shows the weatherunderground observations right now (10 AM Saturday) over a small portion of Seattle.

There are other collections of volunteer weather observations, which are generally less user friendly. One is the Citizen's Weather Observer Program (CWOP) http://www.wxqa.com/.

But let me make one thing very clear. The quality of these volunteer and hobbyist observations vary widely in quality. Some are very good. Some are very bad. Why bad? Generally poor exposure and placement.

Temperature should be measured in the shade or in a protected (white) enclosure at 2-meters above the surface. Rain gauges should be in the open, not near splashing roofs or protective trees. Winds should be taken on masts that are not near buildings or trees (and not a the peak of roofs where wind is accelerated). You get the message.One of the great challenges for professionals like me is how to use this varied, heterogeneous dataset.

12 comments:

A personal weather station is great fun. I installed mine in the dunes about a half mile above the high tide line near Copalis Beach. It is a Vantage Pro 2 wireless. That is, it transmits via microwave radio to a console inside the house about 200 feet away.

My station has been up since October 2008. I have replaced the temperature/humidity sensor and the anemometer under warranty and the temperature humidity sensor again two months ago ($72). My guess is that the temp/hum sensor has about a one year life in this environment. This seems to be a cost of operation in a harsh salt spray environment. Take periodic maintenance requirements into account when you locate your equipment.

Full professional stations may be more robust but will cost several thousand dollars. Davis equipment is good value and they are responsive to tech inquiries by phone.

Plan on investing about $1000 for a wireless, aspirated Davis system. I thought I could get by with the non aspirated version but will be adding the daytime only solar powered fan to my station. Solar heating, even in a normally windy open location, causes errors as much as 3 deg.

Davis software can be configured to upload to both Weather Underground and the Citizens Weather Observation Program (CWOP).

Jeff Masters Weather Underground is the best all around weather site on the net.

I echo Pauls comments about the Davis Vantage Pro wireless station. It's provided us with much enjoyment since 2005. But there are maintenance costs, too. So far mainly batteries, but the capacitor that stores energy from the sun now needs to be replaced. I find long periods with days of low sunlight deplete the charge so the data is not transmitted to the console at times. My sensors are mounted on a roof peak that requires a 32 ft. ladder for access, but it was the best place to measure the wind and rainfall. Because the indoor monitor can read multiple sending units,I'd like to get another wind sensor to mount down on the shoreline where the wind blows unabated from across the 3 mile fetch of Case Inlet.We also have an Oregon Instruments indoor/outdoor thermometer & barometer. They correlate well with the Davis unit at a much lower cost, but with no wind or rain measurements.

I live a few miles NW of Yakima and I was just driving home with a car load of friends and one asked "hey, whats lighting up the entire NW horizon." It was a very pinkish hue. I told them it was the city lights of Seattle and Tacoma. I was basically laughed out of the car.

But I came in, checked the IR satelitte, its clear here but a super thin layer of high clouds over the Sound. Since the horizon is so bright from here, i bet you could see them as far away as moses lake or tri cities. I bet a physicist could easily figure that out. Take the height of the clouds minus the curvature of the earth, i dunno.

I have had an Oregon Scientific weather station for several years and love keeping track of the daily weather. Using Excel I have spreadsheets, graphs, charts, and pivot tables to arrange my stats in numerous different ways.

I noticed my electronic rain guage didn't seem terribly accurate so I signed up with CoCoRaHs http://www.cocorahs.org/ bought one of their required rain guages and now submit my rainfall readings directly to them every morning. They have a really neat nationwide program that evidently helps many other weather related or weather dependent organizations.

So if all you want to do is keep track of precipitation then I highly suggest Community Collaborative Rain Hail and Snow Network.

King County had a similiar rain guage program I belonged to back in the early 80's but it only lasted a few years before it went away due to funding.

WeatherUnderground is a great resource. If you post observations to CWOP/APRSWXNET (wxqa.com), then the will be available to WeatherUnderground by way of MADIS. Through CWOP and MADIS, you will have the benefit of validated station metadata (Russ Chadwick looks at every new station's metadata), and feedback of your station's data quality, by example:http://weather.gladstonefamily.net/site/C0350

I urge everyone with the ability to share their data to do so through CWOP/APRSWXNET... it is the only way NOAA will be able to access your weather data.

I found the La Crosse Technology WS-2310TWC at a local TrueValue about 2 years ago for about $70 on sale. I decided to grab it and see if I liked having it around. It is a blast. It reports to Wunderground so I now have about 2 years of data for our location.

As far as accuracy it seems to be very accurate. I track it along with an analogue thermometer that is mounted near it. Temps are always the same and close to most of the surrounding stations accounting for slight differences in locations.

The only really weak part is the anemometer. It is just a small turbine style tube under the wind vane. When the wind gusts from multiple directions, by the time the vane has lined up with the wind the gust is past.

I figured I would get a more expensive one at some point. So far this one seems to do fine for what I want so I've been happy with it.

Great information! We have an Oregon Scientific at home in Kirkland, but want a better system for our Whidbey property where we get some really good wind and dramatic weather. Perhaps my husband will get a Davis Vantage Pro as a Father's Day present...

I bought a weather station from eBay last year and I can say that this weather station works great, it provides accurate, real-time weather data of indoor and outdoor temperature, and humidity in our area.

Check this link for the item I'm talking about: http://www.ebay.com/itm/433Hz-Wireless-Weather-Station-Thermometers-Hygrometers-In-Outdoor-RCC-DCF77-/321768380597

I like Davis' Vantage Vue. For those unfamiliar, here are some details. It has the same accuracy stats as their Pro 2, but costs less $$$. The biggest downside vs the Pro2 I see is that you can't separate the anemometer from the thermometer. I don't think it makes a big enough difference for me.